<form method="post" action="">
出生日期：
   <input type="text" name="byear" value="yyyy" size="4" maxlength="4"/>年
   <select name="bmon">
         <option value="">[选择月份]</option>
         <potion value="1">一月</option>
         <potion value="2">二月</option>
         <potion value="3">三月</option>
         <potion value="4">四月</option>
         <potion value="5">五月</option>
         <potion value="6">六月</option>
         <potion value="7">七月</option>
         <potion value="8">八月</option>
         <potion value="9">九月</option>
         <potion value="10">十月</option>
         <potion value="11">十一月</option>
         <potion value="12">十二月</option>
   </select>月
   <input type="text" name="bday" value="dd" size="2" maxlength="2" maxlength="2" /> 日
</form>